Method and apparatus for the manufacture of electrical contact plugs



June 11, 1935. E. KLEINMANN EIAL METHOD AND APPARATUS FOR THEMANUFACTURE? OF ELECTRICAL CONTACT PLUGS Filed s t.. -2 19:55 4Sheets-Sheet 1 Arr-away June 11, 1935. E. KL EINMANN ET AL 2,004,555METHOD AND APPARATUS FOR THE MANUFACTURE OF ELECTRICAL CQNTACT PLUGSFiled Sept. 2, 193

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HTTOIINFJ- June 11, 1935. E. KLEINMANN ET AL 2,004,555

METHOD AND APPARATUS FOR THE MANUFACTURE OF ELECTRICAL CONTACT 'PLUGSFiled Sept. 2, 1933 4 Sheets-Sheet 4 ATTORNEX Patented June 11, 1935UNITED STATES "METHOD AND APPARATUS FOR THE MANU- FACTURE PLUGS ErnstKleinmann and or ELECTRICAL CONTACT Alfred I Mendel, Berlin-Lichtenblerg, Germany Application September 2, 1933, Serial No. 688,043

I 19 Claims This invention relates to methods of and apparatus for themanufacture of electrical contact plugs: or pins such as are commonlyemployedin electron discharge tubes or elsewhere where electricalconnection is to be made with a socket. Such-plugs or pins are nowcommonly made in what is called banana shape; that is, they aresubstantially cylindrical but are bulged outwards between their endssoas to enable them to make resilient contact with. the sockets intowhich they are inserted. The invention has for'its chief object toprovide a method of and apparatus for the'rapid and cheap manufacture ofsuch banana plugs.

According to the invention, the plugs are made from a metal strip whichis stamped soas to form a series of pieces, each ofa size and shapesuitable for one plug, these pieces remaining attached to thestrip alongpart of each of two'opposite ends, and the pieces are then successivelyacted upon to bend them into cylindrical form, detach them from thesheet at one end andthen to compress them axially before detaching themat the other end to complete the bulged plugs. The bending is preferablycarried out gradually by a series of operations. The pieces will usuallybe of a rectangular formthatremain attached to the strip by a smallfillet at the middle of each of the shorter sides and the long sidesbent round towards one another without the use of a mandrel to form thecylinder; and slits parallel to the longer sides but not extending tothe shorter sides will usually be formed in the pieces before bulgingand preferably on or just after, stamping to form the pieces. Theinvention also includes apparatus by means of which the method may becarriedout as well as other features that will be hereinafter referredto and claimed.

In order that the invention may be clearly understood and readilycarried into effect, it will now be more fullydescribed by way ofexample with reference to the accompanying drawings. in which:

' Figure 1 is a plan of a strip of sheet metal illus- 45 trating themethod of making bananaplugs according to the invention.

Figure 2 is a plan, partly in section, of apparatus for carrying out themethod illustrated in Figure l.

Figure 3 is one side elevation of the apparatus of Figure 2, the toolscomprised in it being shown in their elevated position.

Figure 4 is the other side elevation of the apparatus of Figure 2, thetools being shown in their lowest position.

Figure 5 is anend elevation of the apparatus of Figure 2, the toolsbeing again shown in their lowest position. I I I Referring first toFigure '1, 0 denotes the strip of sheet metal from which the bananaplugs are 5 to be made. The width of this strip is'slightly larger thanthe'length of the plugs to be made. Double-T-shaped openings 3 "and 4are punched in the strip so as to form a seriesof pieces I each of the"appropriateisize for forming a single plug, these pieces remainingjoined at the mid-point of eachend tothe remainder of the strip 0 by thelugs'or fillets 2 The pieces'are rectangular. The punching of thedouble-*T-Shaped openings is followed by an operation in whichtwoparallel 5 slits are stamped in the sheets. These are for the purpose ofgiving added resiliency'to the plugs. These slits extend from a pointnear one end of the piece to a point just short of the extensions justreferred to. The'slit'piece I is then rolled into cylindrical form. Thisis done in a succession of steps in which the unsecured or longer sidesof the pieces are bent first so that the sheet has semi-cylindricalformand is then acted upon so that the freeedges touch to form a closedcylinder.- The lug and the remaining part'of the metal strip adjacent itis then cut away from one end of the cylinder so that one end is free asshown just above the-middle of Figure 1. The free end of each cylinderis then'turned slightly inwards as shown by the fourth plug from the topof Figure 1.; The cylinder is then compressed axially to cause the plugto bulge at its middle. Subsequently the-plugs'may-be gauged in order toensure that they conform to the required dimensions as shown at the topof Figure 1,' after which the remaining lug iscut and the finished plugallowed to'fall into a collecting container. f Apparatus forcontinuously carrying out the stepsjust described is illustrated inFigures 2-5 of the accompanying drawings. The tool executes all theoperations necessary for the production of a banana plug according tothe method just described with reference toFigur'e 1. The forma-' tionof the T'-shaped slots to form'the pieces I is efiected by means of thepunch 50. The punch 5, which co-operates with thedie 5, forms the slitsand also produces the bead '60. Bending of the pieces'l into cylindricalform is efiected' in five stages by means of the punches 6-40, whichco-operate with the dies 6'--l0' respectively. The cutting of the-lug atone end of the cylinder,. formed by the punches and dies just referredto, is effected by the device 25 (Figure 2) which is arranged behind thepunch ID as seen in Figure 3 and .comes into operation when the punch I0and die I0 have performed their operation. The cupping of the end of thecylinder tube which is left free as a result of the cutting away of thelug by the device 25, is effected by the punch 26 which operates on theend of the longitudinally slit cylindrical tube I While it is gripped inthe dies I I; II. The axial compression of the slit cylinder as a resultof which it is turned into a banana plug, is efiected by the punch 29which acts on the projecting end of the, plug while it is gripped bythe. beaded endin the dies I2, I2. Gauging of the banana plug iseffected by means of the die 30 which ispushed over the already formedbanana plug whileit is-- gripped by the beaded end in the dies I3, I3;

The banana plug is cut off from the remaining portion of the metal stripby the device 14, I4. The joints between the dies II, I2, I3 and I4, andII, I2,.I3 and I4 are horizontally arranged in a horizontalplane, beingcarried inthe plate 2I which rests on the base plate 20, and the metalstrip 0 is fed over them in step-by-steprnanner by the pairs of rollers5I and152.. The strip is correctly positioned at the end. of each stepby the punch-53 which cuts away. aportionot one edgeof the strip .ateach step,; th e; strip being positioned by virtue of the comingintocontact of the step thus formed in it with the side of the punch. Thepunches 53,511, 5, 6,, 1, 8, 9-, I0, and

the device I4 are mounted at their upper ends in a plate 4|. Their upperends have overhanging enlargements that are received incorrespondingrecesses in the top of the plate 4I and they are securedinposition in it by a plate 42 secured on top of it. .The dies I I, I2, I3are similarly carried at their upper ends in a plate I! and secured inthis plate by a plate IS. The plates I9 and I! are slidably carried ontwo vertically arranged bolts I5,;the upper endsof which, are screwedinto a plate I8 fixed on to and projecting over the 'side ofthe plate42. The plates 19 and I'Iare resiliently urgeddownwards against theheads of the bolts I5 by springs I6. r

The plates M and 42 are arranged to slidevertically on bolts 45. Theyare urged upwards by springs 49 surrounding the bolts 45, which springsare able to displace them in that direction until the heads of the bolts45 come into contact with the bottoms of recesses in the plates 42 andAl. The plates 4I and '42 are also connected to an upper plate 43 by thebolts 44, theends of which are, screwed intothe plate 43, the, shankspassing through theplates 4 I and 42 andtheir heads being situated ontheside of the plate 4I remote from plate 43." Theapparatus is mountedin a press with the baseplate 20 on the bed fill-of the press, the plate43 being engaged by the press ram GI. The plate 43 carries two cammembers ,24 and 28 (see Figures 2 and 5). Each", is in the form of 'avertical member which; moves down with the member 43. The member 28 hasakink at a point in its length and passes through an opening inthe'slide member 21, the face of which carries the two dies 26 and 29the former of which cooperates with the dies II-I I to cup the free endof the cylinder, while the latter cooperates with the dies and I2 tocompress the cylinders axially to bulge them, the cam member 28, onmoving down, causing the members. 26 and 29 to be-forced against theends of the cylinders gripped in the two pairs of dies II, II and I2,l2. The cam member 24 has a similarlykinked vertical opening into whichprojects the endcof a lever."48

( springs 49. diesII, I2 andI3- reach the dies II, I2 and I3 to grip.the; cylinders positioned between them pivoted at 41 in a bearing 46.The other end of the lever engages a plunger 30, the end of whichcarries a gauge 3|. On downward movement of the cam member 24 theplunger 30 is slidden so that the gauge 3| passes over the bulgedcylinder that is gripped by its neck in the dies I3, I3 to ensure thatthe extent of bulging of all the cylinders is uniform. fWhen thefplate43. is moved down,'it first takes 'up the plate 42 and the plate I8 andmoves them down against the action of the The arrangement is such thatthe before the punches 50 and 5 to I 0 come into operation. On turtherdownward motion of the plate 42, theplates I'Iand I9 and the dies II, I2and I3 carried by them remain stationary, the springs I6 being thencompressed, and the punches 50 and 5 to I0 then all act on the metalstrip, and the dies 25 and 29 and the gauge 31 come into operation." Inthe continuousproduction of the plugs the plate 43, is 'rcciprocatedvertically and the metal strip is fed into the apparatus ina'step-by-step manner; 0n eachreciprocation of-the plate.43,

thepunch53 is the first tool to come into oper: ation.- Itcuts-away. aportion of one edge of.-the strip; and thecontact with its side of theledge soformed ensures that the metal strip remains arrested in theproper position during'the rest of the downwardstroke 0f:-the plate 43and on its upward stroke until the pimch 53 is clear of the strip. Onbeing .fed in, the strip isactedupon by the punch 50 which punches thedouble-Te iapedcpenings and forms the slits. On the next step ofthe-metalstrip the piece formed by the. punch 50 comes into positionbetween the punch 5 and die 5 which form the bead on it.

.On-.:the nextfivesteps the piece comes between 1e. punches and diesSand 6', I and I, 8 and 8,

gradual'bending round of the'longer sides of the pieceis'effected toform a cylinder." On the next efiective step'of the strip, thecylinder-is dealt with by the dies II,' II and 23, whereby-lits end iscupped; onthe next by the dies I2, I2 and29; whereby it is bulged: thenby the dies I3, I3 and gauge 31; and finally is cut off by the deviceI4. i to iorm the finished bulged contact plug. When. once the enteringend of the metal strip has reachc'd'the device I4, I4, all the'toolsperform an effective operation on'eachstroke of the plate 43, and afinished plug is producedat each stroke; l 'Itis tobeunderstood thatitheclaims are not limited to the methodjdescrib'edor to the construction'shown in the drawings since clearly modificationsmay be made and,therefore, the claims areintended to: beconstrued to cover all suchmodifications as their language will allow in the light or the priorart. I

We claim:-

i 1. A method for the manufacture of abulged electrical contactplugconsisting in stamping a metal sheet so as to form a piece of theappropriatelshape that remains attached along part of eachof twoopposite ends to said sheet, bending said piece into cylindrical formwhile it remains attachedto said sheet at both ends, then detaching itfrom said sheet atone end, subsequently compressing the cylinder axiallyto bulge it and then detaching itat the other end.

double T-shaped openings in a metal sheet so as to form anappropriately-shaped piece that remains attached at the middle of eachof its two opposite ends to said sheet, bending said piece intocylindrical form while it remains attached to said 7 sheet at both ends,then detaching it from said sheet at one end, subsequently compressingthe cylinder axially to bulge it and then detaching it at the other end.

3. A method for the manufacture of a bulged electrical contact plugconsisting in stamping a metal sheet so as to. form a pieceof theappropriate shape that remains attached along part of each of twoopposite ends to said sheet, forming slits in" said piece, said slitsextending at right angles to said ends but not reaching them, bendingsaid piece into cylindrical form while it remains attached to said sheetat both ends, then detaching it from said sheet at one end, subsequentlycompressing the cylinder axially to bulge it, and then detaching it atthe other end.

4. A method for the continuous manufacture of bulged electrical contactplugs consisting in punching a series of openings in a metal strip ofappropriate width, said openings being so spaced and shapedas to form aseries of pieces each of a shape suitable for one plug, each of saidpieces remaining attached at the middle of each of its two ends to saidstrip, bending said pieces in turn into cylindrical form while theyremain attached to said strip at both ends, then detaching the cylindersfrom said strip at one end, compressing them axially to bulge them, andthen detaching them at the other end.

5. A method for the continuous manufacture of bulged electrical contactplugs consisting in stamping a series of double T-shaped openings in ametal strip of appropriate width so as to form a series of substantiallyrectangular pieces each of a size suitable for one plug and so that eachof said pieces remains attached to said strip by a short fillet at themiddle of each of its shorter sides, forming slits in each of saidrectangular pieces, said slits extending parallel to the longer sides ofsaid pieces without reaching either of the shorter sides, bending saidlonger sides round towards one another to form a cylinder while saidpiece remains attached to said strip by both said fillets, thendetaching the cylinders from said strip at one end, compressing themaxially to bulge them and then detaching them at the other end.

6. A method for the continuous manufacture of bulged electrical contactplugs' consisting in stamping a series of double T-shaped openings in ametal strip of appropriate width so as to form a series of substantiallyrectangular pieces each of a size suitable for one plug and so that eachof said pieces remains attached to said strip by a short fillet at themiddle of each of its shorter sides, forming slits in each of saidrectangular pieces, said slits extending parallel to the longer sides ofsaid pieces without reaching either 'of the shorter sides, forming abead in each of said pieces adjacent one of said shorter sides andextending parallel thereto, bending said longer sides round towards oneanother to form a cylinder while said piece remains attached to saidstrip by both said fillets, then detaching the cylinders from said stripat the end remote from said bead, gripping said cylinders by theirbeaded ends and acting on the other ends to compress them axially tobulge them and then detaching them at the other end.

7. A method for the manufacture of bulged 3 electrical contact plugsaccording to claim 6,'in which the ends of said cylinders remote fromsaid beads are cupped inwards before said cylinders are bulged.

8. Apparatus for the continuous production of bulged electrical contactplugs from a moving sheet metal strip comprising means for punching aseries ofiopenings in said strip so as to form pieces of appropriateshape that remain attached to said strip along part of each of twoopposite ends, and a series of tools foracting on said piecessuccessively and operative to bend them step by step intocylindrical'form whilethey remain at' tached to said strip at both ends,to detach the cylinders from said strip at one end, to compress thecylinders axially to bulge them and then to detach the bulged cylindersat the other end.

9. Apparatus for the continuous 1 production of bulged electricalcontact plugs from a sheet metal strip according to claim 8 andincluding means for-feeding said strip in a step-by-step manner whensaid tools are elevated, said punching means and saidseries of toolsbeing mounted so as to reciprocate together and all being adapted to acton saidstrip during each stroke;

10. Apparatus for. the continuous production of bulged electricalcontact plugs from a sheet metal strip according to claim 8, in whichsaid series of tools includes a plurality of tools for acting on saidpieces to bend them gradually into cylindrical form without the use of amandrel.

11. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claim 8, and including meansfor forming slits in said pieces before bulging, said slits extending atright angles to said two opposite ends without reaching either of them.

12. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claim 8, and including meansfor cupping inwards the one detached end of said cylinders.

13. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claim 8, and including meansfor forming a bead in each of said pieces parallel to and adjacent theend remote from that subsequently first detached from said strip.'

14. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claim 8, and including meansfor gauging said bulged cylinders before they are separated from saidstrip.

15. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claim 8, and including meansfor gripping each of said cylinders by the attached end after the otherend has been detached from said sheet, and a device for acting on saidother end to compress said cylinder axially to bulge it.

16. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claim 8, and including meansfor gripping each of'said cylinders after one end has been detached fromsaid sheet so that the other end projects from said means, and a die foracting on said other end to cup it inwardly.

17. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip comprising means for feeding said stripin a step-by-step manner, means for punching an opening in said strip ateach step so as to form a series of pieces of appropriate shape thatremain attached to said strip along part of each of two opposite ends, aseries of tools for subsequently acting in turn on said pieces to bendthem into cylindrical form while, they remain attached to said strip atboth ends, to detach the cylinders from said strip at one end, tocompress the cylinders axially to bulge them and then to detach thebulged cylinders at the other end, and means for punching said strip toarrest it in position to be acted upon; by said first-mentioned punchingmeans and said tools, both' said punching means and said series .oftools being mounted so as to reciprocate together-rand all being adaptedto, act on; said strip during each stroke.

18. Apparatus for the continuous production of bulged electrical contactplugs from a sheet metal strip according to claimr8, including means forfeeding said strip in a step-by-step manner to said punching means ,andsaid tools, and in which said punching means and said tools comprise aseries of punches and dies, all of said dies being arranged in line andsaid strip being fed over them and all of said punches being mounted ona single reciprocatory member for movement towards and away from said,dies together. r I

19. Apparatusfor the continuous production of bulgedelectrical contactplugs from a'sheet metal strip according to claim 8, including means forfeeding said strip in a step-by-step manner to said punching means andsaid tools, a split die for grippingsaid attached end of each of saidcylinders during axial compression, a device for acting on the detachedend to compress said cylinder axially to bulge them, and in-which saidpunching means and said tools comprise a series of punches and dies, allof said last-mentioned dies and half of said split die being arranged-inline and said strip being fed over them, and all of said punches-and theother half of said split die being mounted on a single reciprocatorymember for movement together towards and away from said dies'andhalfdie, said other half die being so mounted'as to come into operation togrip said cylinders before the coming into operation of said punches,and said reciprocatory member carrying a cam for operating said deviceto efiect axial compression after said cylinders have been grippedbysald split die.

ERNST 'KLEINMANN; ALFRED MENDEL.

